This invention relates in general to package wrapping machinery and deals more particularly with improvements in machines for wrapping articles of generally rectangular parallelepiped form wherein wrapper folding operations are performed while an article and its wrapper are conveyed along a generally predetermined path by a plurality of tumble boxes.
In forming a package of the aforedescribed general type it is advantageous to perform wrapper folding operations while the article is held square within a tumble box. Heretofore wrapping machines have been provided wherein some initial folding operations have been performed while an article is held in or transferred into a tumble box. However, the article ejector mechanism on tumble boxes heretofore available have imposed limitations on the positioning of end folding and tucking plates, essential to the completion of wrapper end forming operations. As a consequence of the aforesaid limitation, in wrapping an article some of the folding operations necessary to complete the package are performed by plows or the like while the partially wrapped article is advanced through the machine and held square only by line pressure exerted by adjacent articles or by pressure exerted by a pusher, where individual articles are conveyed by transfer machanism. Accordingly, it is the general aim of the invention to provide an improved wrapping machine of the afore-described general type wherein the wrapper end folding operations are performed while the article and its wrapper are held substantially square by a tumble box.
When the wrapping material is of a heat sealable type, as, for example, a wax coated paper, a wrapping machine may be provided with a long seam heater wherein the long seam of the wrapper is sealed. In such a machine it is generally necessary to provide means for preventing overheating of the packages within the long seam heater when the machine is stopped for any reason. A machine of the present invention is also provided with an improved long seam heater.